Grading of pancreatic neuroendocrine tumors on endoscopic ultrasound-guided fine-needle aspiration using Ki-67 index and 2017 World Health Organization criteria: An analysis of 32 cases

Management of Pancreatic Neuroendocrine Tumors: Surgical Strategies and Controversies

OBJECTIVE

Pancreatic neuroendocrine tumors (PNETs) are uncommon tumors which are increasing in incidence. The management of these tumors continues to evolve. This review examines the current role of surgery in the treatment of these tumors.

METHODS

Studies published over the past 10 years were identified using several databases including PubMed, MEDLINE, and Science Direct. Search terms included PNETs, treatment, and surgery. Clinical practice guidelines and updates from several major groups were reviewed.

RESULTS

Surgery continues to have a major role in the treatment of sporadic functional and nonfunctional PNETs. Pancreas-sparing approaches are increasingly accepted as alternatives to formal pancreatic resection in selected patients. Options such as watch and wait or endoscopic ablation may be reasonable alternatives to surgery for non-functional PNETs < 2 cm in size. Surgical decision-making in multiple endocrine neoplasia type 1 patients remains complex and in some situations such as gastrinoma quite controversial. The role of surgery has significantly diminished in patients with advanced disease due to the advent of more effective systemic and liver-directed therapies. However, the optimal treatments and sequencing in advanced disease remain poorly defined, and it has been suggested that surgery is underutilized in these patients.

CONCLUSIONS

Surgery remains a major treatment modality for PNETs. Given the plethora of available treatments, ongoing controversies and the changing landscape, management has become increasingly complex. An experienced multidisciplinary team which includes surgery is essential to manage these patients.

Endoscopic Ultrasound-Guided Fine Needle Acquisition for Evaluation of Pancreatic Neuroendocrine Tumors: A Meta-Analysis

AIMS

The aim of this meta-analysis was to assess the diagnostic performance of EUS-FNA/B in patients with panNETs.

METHODS

We conducted a computerized search of the MEDLINE and Embase databases to identify relevant articles. The primary outcomes involved grading concordance rate, diagnostic rate, and correlation coefficient (Cohen's κ) for FNA/B samples compared with surgical specimens. Secondary outcomes included sample adequacy, mean number of passes, and adverse events.

RESULTS

Forty-five studies involving 2978 patients were finally included. The pooled concordance rate between EUS-FNA/B and surgical grading was 0.77 (95% CI: 0.73-0.80; I2=48.2%). A significantly higher level of concordance was observed in G1 subgroup (0.88, 95% CI: 0.84-0.91), whereas the G2 subgroup revealed the lowest level of agreement (0.59, 95% CI: 0.52-0.65; P < 0.001). Pooled diagnostic rate for FNA/B sampling was 0.83 (95% CI: 0.79-0.86; I2=63.3%). In addition, FNB outperformed FNA in terms of sample adequacy (0.93 for FNB vs. 0.81 for FNA; P=0.007) and number of needle passes required (2.53 for FNB vs. 3.32 for FNA; P=0.013). Moreover, the overall level of agreement for grading was moderate (κ=0.59, 95% CI: 0.49-0.68; I2=84.5%). There were a limited number of adverse events that had minor influence on patient outcomes (0.03, 95% CI: 0.02-0.05; I2=19.2%).

CONCLUSIONS

EUS-FNA/B is a reliable approach for the diagnosis and preoperative grading of panNET, with FNB demonstrating superior performance compared with FNA.

Grading medullary thyroid carcinoma on fine-needle aspiration cytology specimens with the International Medullary Thyroid Carcinoma Grading System: A cytologic-histologic correlation

BACKGROUND

Medullary thyroid carcinoma (MTC) is a rare cancer of parafollicular C-cell origin. The International MTC Grading System (IMTCGS) incorporates mitotic activity, the presence of necrosis, and the Ki67 proliferation rate (PR) to classify MTCs as low or high grade. The ability to predict IMTCGS grade in cytology was assessed.

METHODS

MTCs with cytology and subsequent surgical follow-up were reviewed. Cytology slides were reviewed for mitotic figures, apoptoses, and necrosis, and a Ki67 PR was calculated when possible. Findings were correlated with final IMTCGS grade.

RESULTS

Twenty-five MTC fine-needle aspirations (FNAs) were identified, with nine identified as high grade (36%). By using a PR cutoff of 5%, Ki67 on FNA material (Ki67FNA) showed 92% concordance (n = 22 of 24) with surgical Ki67 and a correlation coefficient (R2) of 0.72. Sensitivity and specificity of Ki67FNA for predicting high-grade MTC were 38% and 100%, respectively. Multiple mitotic figures were present in a single slide of 43% (n = 3 of 7) of evaluable high-grade MTCs, whereas only one of 16 low-grade MTCs showed a single mitotic figure. Definitive apoptoses were present in five of seven high-grade MTC FNAs but were absent in 16 low-grade MTCs. The sensitivity and specificity of apoptoses/necrosis on cytology for high-grade MTCs were 71% and 88%, respectively.

CONCLUSIONS

Ki67FNA ≥5% shows low sensitivity but high specificity for predicting high-grade MTC. The presence of multiple mitotic figures in a single slide or definitive apoptotic bodies are both highly suggestive of high-grade MTC, and should warrant a close examination for necrosis and a careful Ki67 PR count.

[Challenges of cytopathological pancreas diagnostics]

The cytologic diagnostics of solid and cystic pancreatic lesions with endoscopic ultrasound-guided fine-needle aspiration (EUS-FNA) is an integral part of the clinical workup and the decision of a surgical versus a conservative approach. Cystic lesions are increasingly being diagnosed due to improved imaging and represent numerous neoplastic as well as non-neoplastic epithelial and non-epithelial entities, which differ in biological behavior and prognosis. In particular, the differentiation of mucinous and non-mucinous cysts is significant for further clinical management. Regressive cellular changes, gastrointestinal contaminants, and overlapping morphologic changes of reactively altered ductal epithelial cells and cells of well-differentiated neoplasms and preneoplasms are special challenges of cytological diagnostics. For a uniform cytological classification of findings, an internationally developed seven-level classification system has been published and co-published by the World Health Organization (WHO). This classification system takes into account both morphological findings and further procedures on cytological material such as next-generation sequencing and immunocytochemistry and is based on the WHO classification for pancreatic tumors. Against this background, important cytologic diagnostic criteria of various solid and cystic lesions relevant in clinical practice are presented in this article, considering diagnostic possibilities and pitfalls as well as differential diagnoses.

Diagnostic Accuracy of ki-67 Labeling Index in Endoscopic Ultrasonography-Fine-Needle Aspiration Cytology and Biopsy of Pancreatic Neuroendocrine Neoplasms

BACKGROUND

This study aimed to compare the diagnostic accuracy of the Ki-67 labeling index (LI) between endoscopic ultrasonography-fine-needle aspiration cytology/biopsy (EUS-FNAC/FNB) and surgical specimens of pancreatic neuroendocrine neoplasms (PanNENs).

METHODS

Conventional meta-analysis and diagnostic test accuracy (DTA) reviews were performed on 17 eligible studies. The DTA review involved calculating the sensitivity, specificity, diagnostic odds ratio (OR), and area under the curve (AUC) of the summary receiver operating characteristic (SROC) curve. In addition, subgroup analysis was conducted based on EUS-FNAC and FNB, tumor grade, and tumor size.

RESULTS

The overall concordance rate of WHO grade based on Ki-67 LI between the EUS-FNAC/FNB and the surgical specimen was 0.767 (95% confidence interval (CI), 0.713-0.814). Concordance rates of the EUS-FNAC and EUS-FNB subgroups were 0.741 (95% CI, 0.681-0.794) and 0.839 (95% CI, 0.738-0.906), respectively. In the DTA review for grade 3, the sensitivity and specificity were calculated to be 0.786 (95% CI, 0.590-0.917) and 0.998 (95% CI, 0.987-1.000), respectively. The diagnostic OR and AUC of the SROC curve were 150.220 (95% CI, 46.145-489.000) and 0.983, respectively. The sensitivity and specificity were observed to be highest in the grade 1 and 3 subgroups, respectively.

CONCLUSIONS

Higher concordance of tumor grade based on Ki-67 LI was observed between EUS-FNAC/FNB and surgical specimens, indicating the potential usefulness of Ki-67 LI in predicting PanNEN tumor grade in EUS-FNAC/FNB.

Grading Pancreatic Neuroendocrine Tumors Via Endoscopic Ultrasound-guided Fine Needle Aspiration: A Multi-institutional Study

OBJECTIVES

To identify factors associated with concordance between World Health Organization (WHO) grade on cytological analysis (c-grade) and histopathological analysis (h-grade) of surgical specimen in patients with PanNETs and examine trends in utilization and accuracy of EUS-FNA in preoperatively predicting grade.

BACKGROUND

WHO grading system is prognostic in pancreatic neuroendo-crine tumors (PanNETs). The concordance between c-grade and h-grade is reported to be between 50% and 92%.

METHODS

A multicenter retrospective study was performed on patients undergoing resection for PanNETs at four high-volume centers between 2010 and 2019. Patients with functional or syndrome-associated tumors, and those receiving neoadjuvant therapy were excluded. Factors associated with concordance between c-grade and h-grade and trends of utilization of EUS-FNA were assessed.

RESULTS

Of 869 patients included, 517 (59.5%) underwent EUS-FNA; 452 (87.4%) were diagnostic of PanNETs and WHO-grade was reported for 270 (59.7%) patients. The concordance between c-grade and h-grade was 80.4% with moderate concordance ( Kc = 0.52, 95% CI: 0.41-0.63). Significantly higher rates of concordance were observed in patients with smaller tumors (<2 vs. ≥2cm, 81.1% vs. 60.4%, P = 0.005). Highest concordance (98.1%) was observed in patients with small tumors undergoing assessment between 2015-2019 with a near-perfect concordance ( Kc = 0.88, 95% CI: 0.61-1.00). An increase in the utilization of EUS-FNA (56.1% to 64.1%) was observed over the last 2 decades ( P = 0.017) and WHO-grade was more frequently reported (44.2% vs. 77.6%, P < 0.001). However, concordance between c-grade and h-grade did not change significantly (P = 0.118).

CONCLUSION

Recently, a trend towards increasing utilization and improved diagnostic accuracy of EUS-FNA has been observed in PanNETs. Concordance between c-grade and h-grade is associated with tumor size with near-perfect agreement when assessing PanNETs <2cm in size.

Tumour Heterogeneity and the Consequent Practical Challenges in the Management of Gastroenteropancreatic Neuroendocrine Neoplasms

Tumour heterogeneity is a common phenomenon in neuroendocrine neoplasms (NENs) and a significant cause of treatment failure and disease progression. Genetic and epigenetic instability, along with proliferation of cancer stem cells and alterations in the tumour microenvironment, manifest as intra-tumoural variability in tumour biology in primary tumours and metastases. This may change over time, especially under selective pressure during treatment. The gastroenteropancreatic (GEP) tract is the most common site for NENs, and their diagnosis and treatment depends on the specific characteristics of the disease, in particular proliferation activity, expression of somatostatin receptors and grading. Somatostatin receptor expression has a major role in the diagnosis and treatment of GEP-NENs, while Ki-67 is also a valuable prognostic marker. Intra- and inter-tumour heterogeneity in GEP-NENS, however, may lead to inaccurate assessment of the disease and affect the reliability of the available diagnostic, prognostic and predictive tests. In this review, we summarise the current available evidence of the impact of tumour heterogeneity on tumour diagnosis and treatment of GEP-NENs. Understanding and accurately measuring tumour heterogeneity could better inform clinical decision making in NENs.

Reliability of grading preoperative pancreatic neuroendocrine tumors on EUS specimens: a systematic review with meta-analysis of aggregate and individual data

BACKGROUND AND AIMS

Therapy and prognosis of pancreatic neuroendocrine tumors (PanNETs) are strictly related to the Ki-67 index, which defines tumor grading. The criterion standard for the assessment of grading of PanNETs is EUS-guided FNA (EUS-FBAFNA) or EUS-guided fine-needle biopsy sampling (EUS-FNB). Because data on diagnostic accuracy of EUS-FNA and EUS-FNB are heterogeneous, we aimed to analyze the variability in concordance between EUS grading and surgical grading.

METHODS

The MEDLINE, SCOPUS, and EMBASE databases were searched until November 2021 to identify studies reporting the concordance rate between EUS grading and surgical grading. The study was conducted in accordance with Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Pooled events were calculated using a random-effects model and expressed in terms of pooled prevalence rates. A multivariate meta-regression was performed to find possible sources of heterogeneity. Where available, individual data were analyzed.

RESULTS

Twenty-six studies with 864 patients undergone EUS-FNA or EUS-FNB and surgical resection for PanNETs were included. The pooled estimate rate for the overall concordance of EUS grading and surgical grading was 80.3% (95% confidence interval, 75.6-85.1). Undergrading (EUS grading < surgical grading) was significantly more frequent with respect to overgrading (14.7% vs 3.5%, P < .001). Individual data analysis showed that among nonconcordant patients, the median Ki-67 difference was 3% (interquartile range, 2-6.15). The type of World Health Organization classification adopted and the median lesion diameter were significantly associated with heterogeneity at meta-regression.

CONCLUSIONS

EUS is an accurate technique in defining grading in patients with PanNETs, but a margin of error still exists, which should be the focus of future studies to minimize the risk of over- and/or undertreatment.

A novel tool to predict nodal metastasis in small pancreatic neuroendocrine tumors: A multicenter study

BACKGROUND

Nonfunctional pancreatic neuroendocrine tumors display a wide range of biological behavior, and nodal disease is associated with metastatic disease and poorer survival. The aim of this study was to develop a tool to predict nodal disease in patients with small (≤2 cm) nonfunctional pancreatic neuroendocrine tumors.

METHODS

A multicenter retrospective study was performed on patients undergoing resection for small nonfunctional pancreatic neuroendocrine tumors. Patients with genetic syndromes, metastatic disease at diagnosis, neoadjuvant therapy, or positive resection margin were excluded. Factors associated with nodal disease were identified to develop a predictive model. Internal validation was performed using bootstrap with 1,000 resamples.

RESULTS

Nodal disease was observed in 39 (11.1%) of the 353 patients included. Presence of nodal disease was significantly associated with lower 5-year disease-free survival (71.6% vs 96.2%, P < .001). Two predictors were strongly associated with nodal disease: G2 grade (odds ratio: 3.51, 95% confidence interval: 1.71-7.22, P = .001) and tumor size (per mm increase, odds ratio: 1.14, 95% confidence interval: 1.03-1.25, P = .009). Adequate discrimination was observed with an area under the curve of 0.71 (95% confidence interval: 0.63-0.80). Based on risk distribution, 3 risk groups of nodal disease were identified; low (<5%), intermediate (≥5% to <20%), and high (≥20%) risk. The observed mean risk of nodal disease was 3.7% in the low-risk patients, 9.6% in the intermediate-risk patients, and 30.4% in the high-risk patients (P < .001). The 10-year disease-free survival in the low, intermediate, and high-risk groups was 100%, 88.8%, and 50.1%, respectively.

CONCLUSION

Our model using tumor grade and size can predict nodal disease in small nonfunctional pancreatic neuroendocrine tumors. Integration of this tool into clinical practice could help guide management of these patients.

Digestive Well-Differentiated Grade 3 Neuroendocrine Tumors: Current Management and Future Directions

Digestive well-differentiated grade 3 neuroendocrine tumors (NET G-3) have been clearly defined since the 2017 World Health Organization classification. They are still a rare category lacking specific data and standardized management. Their distinction from other types of neuroendocrine neoplasms (NEN) not only lies in morphology but also in genotype, aggressiveness, functional imaging uptake, and treatment response. Most of the available data comes from pancreatic series, which is the most frequent tumor site for this entity. In the non-metastatic setting, surgical resection is recommended, irrespective of grade and tumor site. For metastatic NET G-3, chemotherapy is the main first-line treatment with temozolomide-based regimen showing more efficacy than platinum-based regimen, especially when Ki-67 index <55%. Targeted therapies, such as sunitinib and everolimus, have also shown some positive therapeutic efficacy in small samples of patients. Functional imaging plays a key role for detection but also treatment selection. In the second or further-line setting, peptide receptor radionuclide therapy has shown promising response rates in high-grade NEN. Finally, immunotherapy is currently investigated as a new therapeutic approach with trials still ongoing. More data will come with future work now focusing on this specific subgroup. The aim of this review is to summarize the current data on digestive NET G-3 and explore future directions for their management.

Role of Endoscopic Ultrasound in the Diagnosis of Pancreatic Neuroendocrine Neoplasms

Although pancreatic neuroendocrine neoplasms (PNENs) are relatively rare tumors, their number is increasing with advances in diagnostic imaging modalities. Even small lesions that are difficult to detect using computed tomography or magnetic resonance imaging can now be detected with endoscopic ultrasound (EUS). Contrast-enhanced EUS is useful, and not only diagnosis but also malignancy detection has become possible by evaluating the vascularity of tumors. Pathological diagnosis using EUS with fine-needle aspiration (EUS-FNA) is useful when diagnostic imaging is difficult. EUS-FNA can also be used to evaluate the grade of malignancy. Pooling the data of the studies that compared the PNENs grading between EUS-FNA samples and surgical specimens showed a concordance rate of 77.5% (κ-statistic = 0.65, 95% confidence interval = 0.59–0.71, p < 0.01). Stratified analysis for small tumor size (2 cm) showed that the concordance rate was 84.5% and the kappa correlation index was 0.59 (95% confidence interval = 0.43–0.74, p < 0.01). The evolution of ultrasound imaging technologies such as contrast-enhanced and elastography and the artificial intelligence that analyzes them, the evolution of needles, and genetic analysis, will further develop the diagnosis and treatment of PNENs in the future.